Field of the Invention
The invention relates to a control circuit, and more particularly to a control circuit for boost converter and a method for controlling a boost converter.
Description of the Related Art
An electronic device generally includes various components requiring different operating voltages. Therefore, a DC-DC voltage converter is essential for the electronic device to adjust and stabilize voltage levels. Based upon different power requirements, various types of DC-DC voltage converters, originating from a buck (step down) converter and a boost (step up) converter, have been developed. Accordingly, the buck converter can decrease an input DC voltage to a default voltage level, and the boost converter can increase an input DC voltage. With advances in circuit technology, both the buck and boost converters are varied and modified to conform to different system architectures and requirements.
Generally, a boost converter can operate in a Pulse Width Modulation (PWM) mode and a Pulse Frequency Modulation (PFM) mode. Both the PWM mode and PFM mode have their corresponding merits and drawbacks. For example, if the boost converter directly operates in the PWM mode when the electronic device is just starting up (also known as a boot-up), an over-current problem (that is, the amount of current exceeding a predetermined threshold) will occur.
Therefore, a boost converter and a method for controlling a boost converter to avoid the over-current problem when the electronic device starts up (or boots up) are required to avoid generating an excessively large inductor current, and to protect the electronic components from being damaged by the excessively large current.